The adsorption of four linear aliphatic alcohols (C-3, C-4, C-7 and C-8) at the free surface of DMSO has been studied by measuring the surface tension variation and the surface potential shift. The experimental data of surface pressure have been fitted by means of a Frumkin isotherm. The adsorption parameters are discussed in terms of (i) surface distribution and orientation of adsorbate molecules, (ii) Gibbs energy of adsorption, and (iii) lateral interactions. Presumable adsorption modes are pointed out. The adsorption potential shift is discussed with the aid of recent models.